In conventional optical reactors or photo-reactors, a light source is used to treat a fluid in a reaction chamber formed by an enclosure. The light source may be immersed in the fluid, possibly with a transparent sleeve around it. Alternatively, the light source may be arranged outside the fluid, and optical means like reflectors may be used to direct the light produced by the light source towards and into the fluid. The combination of at least the light source and the enclosure, either formed as a flow-through enclosure or as a batch container, will be referred to as a reactor.
One known approach contemplates an elongated light source (UV light producing discharge lamp) having a transparent sleeve made of quartz glass around it. A cylindrical housing contains the light source and the sleeve, as well as a driving circuit. The driving circuit is located at or near one end of the light source, either inside the sleeve or outside the sleeve in close proximity thereto. From the driving circuit, electrical connections are to be made to both ends of the light source. A fluid to be treated flows in a reaction chamber defined by (between) the sleeve and the housing. A cooling of the housing, and thereby also a cooling of the driving circuit, is performed by the fluid.
One disadvantage of this approach is that the electrical connection between the light source and a driver circuit has electrical impedance, which acts as a series inductance and a parallel capacitance between the light source and the driving circuit. This parasitic electrical impedance prevents the use of high frequencies in driving the light source, and thereby prevents the use of particular light sources operating at such high frequencies.
Another disadvantage of the approach above is its low electrical safety and electrical shielding. The electrical driving circuit, an electrical connection from the driving circuit to the light source, and light source electrical contacts must be insulated. Constructional measures must be taken to protect an operator from electrical shock, to reduce generation of electromagnetic radiation and distortions, and to minimize pick-up of electromagnetic disturbances.